Optical assembly for optical fiber gyroscope and optical fiber gyroscope

Abstract

The invention discloses an optical assembly for an optical fiber gyroscope and the optical fiber gyroscope. The optical assembly comprises an optical integration unit, a mode field conversion unit and a light polarization modulation unit, the optical integration unit comprises an optical coupling unit and an optical detector; a first end of the optical coupling unit is coupled with a light source, a second end of the optical coupling unit is coupled with a first end of the mode field conversion unit, a third end of the optical coupling unit is coupled with an optical detector, and a second end of the mode field conversion unit is coupled with a first end of the optical polarization modulation unit; wherein the mode field conversion unit is used for performing mode field conversion on an optical signal output by the second end of the optical coupling unit and then inputting the optical signal into the optical polarization modulation unit, and performing mode field conversion on an optical signal output by the first end of the optical polarization modulation unit and then coupling and inputting the optical signal into the optical detector through the optical coupling unit. By using the optical assembly, the mode field matching loss can be effectively reduced, and the optical transmission efficiency can be improved. Furthermore, the measurement precision of the optical fiber gyroscope can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic gyroscopes, and in particular to an optical component used for a fiber optic gyroscope and a fiber optic gyroscope. Background Art

[0002] The fiber optic gyroscope is an angular velocity sensor based on the Sagnac effect. It has the characteristics of large dynamic range, resistance to impact and vibration, strong resistance to environmental interference, and full precision coverage. Therefore, it is widely used in fields such as attitude control of micro-satellites and navigation control of aerial bombs and rocket launchers.

[0003] The components of the existing conventional fiber optic gyroscope mainly include a light source, an optical coupling unit, an optical polarization modulation unit, an optical detection unit, an optical fiber ring, etc. Among them, the optical signal output by the optical coupling unit is input into the optical polarization modulation unit for polarization modulation processing, and then enters the optical fiber ring; the optical signal that undergoes the Sagnac effect in the optical fiber ring is input into the optical detection unit via the optical polarization modulation unit and the optical coupling unit in sequence. The above-mentioned units are usually packaged into discrete device units in an independent packaging manner. When the discrete device units form a fiber optic gyroscope, the units need to be connected by optical fiber fusion splicing.

[0004] However, on the one hand, due to the influence of the device material characteristics, size and other factors, if the optical coupling unit and the optical polarization modulation unit are directly coupled (also called "coupling"), there will be a mismatch in the optical mode field between the two, thereby reducing the optical signal transmission efficiency of the fiber optic gyroscope. On the other hand, when assembling the fiber optic gyroscope, the individual discrete device units are connected by optical fiber fusion splicing, and when the optical fibers are fused together, there is also a problem of fusion loss, which also reduces the optical signal transmission efficiency. Summary of the invention

[0005] The technical problem solved by the embodiments of the present invention is how to reduce the mode field matching loss of the fiber optic gyroscope and improve the light transmission efficiency.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides an optical component for a fiber optic gyroscope, comprising: an optical integration unit, a mode field conversion unit and an optical polarization modulation unit; the optical integration unit comprises: an optical coupling unit and a light detector; the first end of the optical coupling unit is coupled to a light source, the second end of the optical coupling unit is coupled to the first end of the mode field conversion unit, the third end of the optical coupling unit is coupled to the light detector, and the second end of the mode field conversion unit is coupled to the first end of the optical polarization modulation unit; wherein the mode field conversion unit is used to perform mode field conversion on an optical signal output from the second end of the optical coupling unit and then input the optical signal into the optical polarization modulation unit, and to perform mode field conversion on an optical signal output from the first end of the optical polarization modulation unit and then couple the optical signal into the light detector via the optical coupling unit.

[0007] Optionally, the mode field conversion unit is formed on a first chip, the first chip includes a silicon nitride layer, and a first waveguide formed in the silicon nitride layer; the first end of the first waveguide is coupled to the second end of the optical coupling unit, and the second end of the first waveguide is coupled to the first end of the optical polarization modulation unit.

[0008] Optionally, the second end of the first waveguide has a dual waveguide structure.

[0009] Optionally, one or more of the following is satisfied: the spacing between the two waveguides of the dual waveguide structure is in the interval [1.1 μm, 1.3 μm]; the width of the two waveguides of the dual waveguide structure is in the interval [0.15 μm, 0.18 μm]; the height of the two waveguides of the dual waveguide structure is in the interval [0.25 μm, 0.35 μm].

[0010] Optionally, the total waveguide length of the first waveguide is a first preset multiple of the width of the region where the first waveguide is located; wherein the width direction of the region where the first waveguide is located is consistent with the extension direction of the first end of the first waveguide.

[0011] Optionally, the shape of the middle region of the first waveguide excluding the first end and the second end is selected from: a circular spiral shape and a square spiral shape.

[0012] Optionally, the optical polarization modulation unit is formed on a second chip, the second chip includes a lithium niobate layer, and a second waveguide formed in the lithium niobate layer; the first end of the second waveguide is coupled to the second end of the first waveguide.

[0013] Optionally, the second waveguide is in a Y-shape; the optical signal output from the second end of the first waveguide is divided into two-path optical signal outputs via the Y-shaped second waveguide.

[0014] Optionally, the second end of the first waveguide is staggered coupled with the first end of the second waveguide.

[0015] Optionally, the misalignment between the second end of the first waveguide and the first end of the second waveguide in a direction perpendicular to the first end of the second waveguide is in the interval [0.5 μm, 0.7 μm].

[0016] Optionally, the first end of the first waveguide is coupled to the chip to which the optical coupling unit belongs by using an inter-chip coupling method; and / or the second end of the first waveguide is coupled to the first end of the second waveguide by using an inter-chip coupling method.

[0017] Optionally, the optical integrated unit is formed on a silicon photonic chip, and the optical coupling unit and the light detector are formed on the silicon photonic chip; the optical coupling unit includes a first optical coupler, an optical beam splitter and a second optical coupler; the first end of the first optical coupler is coupled to the light source; the first end of the optical beam splitter is coupled to the second end of the first optical coupler; the first end of the second optical coupler is coupled to the second end of the optical beam splitter, and the second end of the second optical coupler is coupled to the first end of the first waveguide; the light detector is coupled to the third end of the optical beam splitter.

[0018] Optionally, one or more of the following conditions are satisfied: the waveguide width of the first end of the first waveguide is in the interval [0.27 μm, 0.30 μm]; the waveguide width of the second end of the second optical coupler is in the interval [0.12 μm, 0.14 μm].

[0019] Optionally, an embodiment of the present invention further provides a fiber optic gyroscope, comprising the above-mentioned optical component and a polarization-maintaining fiber ring; the polarization-maintaining fiber ring is coupled to the second end of the optical polarization modulation unit, and the optical signal output by the optical polarization modulation unit undergoes a Sagnac effect in the polarization-maintaining fiber ring and then returns to be input into the optical polarization modulation unit.

[0020] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0021] Due to the influence of factors such as device material properties and size, there is a mismatch between the optical mode field size at the second end of the optical coupling unit and the optical mode field size at the first end of the optical polarization modulation unit, resulting in a large mode field matching loss between the optical coupling unit and the optical polarization modulation unit. Therefore, in an embodiment of the present invention, a mode field conversion unit is added between the optical coupling unit and the optical polarization modulation unit to perform mode field conversion through the mode field conversion unit, thereby improving the matching degree between the mode field at the second end of the optical coupling unit and the mode field at the first end of the optical polarization modulation unit. In this way, the mode field matching loss between the optical coupling unit and the optical polarization modulation unit can be effectively reduced, and the optical signal transmission efficiency can be improved. Further, the measurement accuracy of the fiber optic gyroscope can be improved.

[0022] Furthermore, in the embodiment of the present invention, compared with the single waveguide structure, by setting the second end of the first waveguide as a dual waveguide structure, it is helpful to excite a larger mode field at the second end of the first waveguide and the mode field can be stably bound, so that the mode field can better match the mode field of the first end of the optical polarization modulation unit 23. Thus, the mode field matching loss between the second end of the first waveguide and the first end of the optical polarization modulation unit 23 can be reduced, and the optical signal transmission efficiency can be improved. Furthermore, by appropriately setting the width of the two waveguides of the dual waveguide structure and the waveguide spacing, the mode field matching degree can be maximized, thereby maximizing the optical transmission efficiency.

[0023] Furthermore, in an embodiment of the present invention, on the basis of utilizing the first waveguide to realize the mode field conversion function, by setting the first waveguide to have a sufficient length value, the first waveguide can also have a high-order mode suppression / filtering function for the return optical signal, so that the optical detector can receive a more accurate and reliable fundamental mode optical signal, reduce high-order mode interference, and improve the measurement accuracy of the fiber optic gyroscope.

[0024] Furthermore, in an embodiment of the present invention, the shape of the first waveguide can be appropriately set (for example, a spiral shape) under the premise of considering the process complexity, so that the first waveguide occupies a smaller chip area to achieve the total length required for high-order mode filtering, thereby minimizing the device size.

[0025] Furthermore, in an embodiment of the present invention, the first end of the first waveguide may be coupled to the chip to which the optical coupling unit belongs by using an inter-chip coupling method; and / or, the second end of the first waveguide may be coupled to the first end of the second waveguide by using an inter-chip coupling method. Compared with the existing fiber optic gyroscope that couples each unit by using an optical fiber fusion splicing method, the inter-chip coupling method can avoid the splicing loss problem caused by optical fiber fusion splicing on the one hand, and further improve the optical signal transmission efficiency; on the other hand, compared with the optical fiber fusion splicing method, the inter-chip coupling method is less likely to break, the device structure is more stable, and it is easier to package later.

[0026] Further, in the embodiment of the present invention, the mode field loss between the second end of the second optical coupler and the first end of the first waveguide, and the mode field loss between the second end of the first waveguide and the first end of the second waveguide are not only affected by the device material properties (e.g., refractive index), but also by factors such as the waveguide size of the coupling end. Based on this, when a chip with a constant waveguide height is selected, the mode field loss between the units can be minimized by appropriately setting the waveguide width at the second end of the second optical coupler, the waveguide width at the first end of the first waveguide, and the waveguide width at the second end of the first waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the composition structure of a fiber optic gyroscope in the prior art;

[0028] Figure 2 It is a schematic structural diagram of an optical component for a fiber optic gyroscope in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Reference Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of a fiber optic gyroscope in the prior art.

[0030] The fiber optic gyroscope comprises: a superluminescent diode 11, a fiber coupler 12, a Y waveguide modulator 13, a fiber ring 14 and a photodetector 15. Each of the above components is independently packaged into a discrete device unit. When each discrete device unit forms a fiber optic gyroscope, each unit needs to be connected by a fiber fusion method. Figure 1 As shown, the black dots represent the fiber fusion points between the various units, and the arrow direction represents the transmission direction of the optical signal.

[0031] Specifically, the optical signal output by the fiber coupler 12 is input to the Y-waveguide modulator 13, and the Y-waveguide modulator 13 modulates the input optical signal and divides it into two optical signals, which are input to the fiber ring 14. After the Sagnac effect occurs in the fiber ring 14, the two optical signals are divided into two optical signals and return to the Y-waveguide modulator 13. The Y-waveguide modulator 13 couples the returned two-way optical signal into a single optical signal and then couples it into the optical detector 15 via the fiber coupler 12.

[0032] However, on the one hand, due to the influence of factors such as device material properties and size, if the optical fiber coupler 12 is directly coupled to the Y-waveguide modulator 13 (such as Figure 1 As shown in FIG. 1 , the mode field at the output end of the fiber coupler 12 does not match the mode field at the input end of the Y-waveguide modulator 13. The diameter of the mode field represents 1 / e^2 times the energy of the optical signal in the waveguide section. Specifically, the mode field diameter at the output end of the fiber coupler 12 is about 3 μm, while the mode field diameter at the input end of the Y-waveguide modulator 13 is often required to be larger (for example, required to reach 6 μm). Therefore, there is a large mode field matching loss between the fiber coupler 12 and the Y-waveguide modulator 13, which leads to a reduction in the optical signal transmission efficiency.

[0033] on the other hand, Figure 1 The individual components of the fiber optic gyroscope shown are connected by fiber fusion splicing. When the fibers are fused together, there will be a large splicing loss at the fiber fusion point, which also reduces the efficiency of optical signal transmission. Furthermore, if the fiber fusion splicing method is not properly protected during subsequent use, the fusion point is prone to breakage, making the device structure unstable.

[0034] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] Reference Figure 2 , Figure 2 It is a schematic structural diagram of an optical component for a fiber optic gyroscope in an embodiment of the present invention.

[0036] The optical component for the fiber optic gyroscope may include: an optical integration unit 21, a mode field conversion unit 22 and an optical polarization modulation unit 23; the optical integration unit 21 includes an optical coupling unit 211 and a light detector 212; the first end a1 of the optical coupling unit 211 is coupled to the light source, the second end a2 of the optical coupling unit 211 is coupled to the first end b1 of the mode field conversion unit 22, the third end a3 of the optical coupling unit 211 is coupled to the light detector 212, and the second end b2 of the mode field conversion unit 22 is coupled to the first end c1 of the optical polarization modulation unit 23.

[0037] The mode field conversion unit 22 is used to perform mode field conversion on the optical signal output from the second end a2 of the optical coupling unit 211 and then input it into the optical polarization modulation unit 23, and to perform mode field conversion on the optical signal output from the first end c1 of the optical polarization modulation unit 23 and then couple it into the optical detector 212 via the optical coupling unit 211 (the transmission direction of the optical signal is shown in FIG. Figure 2 (direction of the small arrows next to each waveguide).

[0038] The light source may be a superluminescent diode. The light source may be used as one of the components of the optical component, or may be used as an external component of the optical component.

[0039] It should be pointed out that, due to the influence of factors such as device material properties and size, there is a mismatch between the mode field size of the second end a2 of the optical coupling unit 211 and the mode field size of the first end c1 of the optical polarization modulation unit 23, which leads to a large mode field matching loss between the optical coupling unit 211 and the optical polarization modulation unit 23.

[0040] In order to solve the above-mentioned problem, in the embodiment of the present invention, a mode field conversion unit 22 is added between the optical coupling unit 211 and the optical polarization modulation unit 23, so as to perform mode field conversion through the mode field conversion unit 22, thereby improving the matching degree between the mode field of the second end a2 of the optical coupling unit 211 and the mode field of the first end c1 of the optical polarization modulation unit 23. Thus, the mode field matching loss between the optical coupling unit 211 and the optical polarization modulation unit 23 can be effectively reduced, thereby improving the optical signal transmission efficiency of the optical fiber gyroscope.

[0041] Furthermore, the mode field conversion unit 22 can be formed on a first chip, the first chip includes a silicon nitride layer, and a first waveguide 221 formed on the silicon nitride layer; the first end of the first waveguide 221 is coupled to the second end a2 of the optical coupling unit, and the second end of the first waveguide 221 is coupled to the first end c1 of the optical polarization modulation unit 23.

[0042] The first end of the first waveguide 221 is located at the first end b1 of the mode field conversion unit 22 , and the second end of the first waveguide 221 is located at the second end b2 of the mode field conversion unit 22 .

[0043] In a specific implementation, the silicon nitride layer can be formed by low pressure chemical vapor deposition (LPCVD) or plasma enhanced chemical vapor deposition (PECVD). The silicon nitride layer can be formed on a substrate (e.g., a silicon substrate) and a silicon dioxide layer is used as an upper cladding layer to achieve stable transmission of the mode in the silicon nitride layer.

[0044] In a specific implementation, the first waveguide 221 can be formed by etching the silicon nitride layer. Since the silicon nitride material itself has a low loss characteristic, the embodiment of the present invention forms the first waveguide 221 on the silicon nitride layer, which can effectively reduce the loss during the optical signal transmission process.

[0045] In a specific implementation, the first waveguide 221 may be a strip waveguide.

[0046] Furthermore, the second end of the first waveguide 221 has a double waveguide structure 2211 .

[0047] In a specific implementation, the dual waveguide structure 2211 satisfies one or more of the following: the spacing between the two waveguides of the dual waveguide structure 2211 is in the interval [1.1μm, 1.3μm]; the width of the two waveguides of the dual waveguide structure 2211 is in the interval [0.15μm, 0.18μm]; the height of the two waveguides of the dual waveguide structure 2211 is in the interval [0.25μm, 0.35μm].

[0048] In this embodiment, the spacing direction between the two waveguides is parallel to the surface of the substrate (or silicon nitride layer) of the first chip and perpendicular to the extension direction of the second end of the first waveguide 221. The width directions of the two waveguides are consistent with the spacing direction, and the height directions of the two waveguides are perpendicular to the substrate of the first chip.

[0049] As a non-limiting embodiment, when the thickness / height of the silicon nitride layer of the first chip (i.e., the height of the dual waveguide structure 2211) is constant (e.g., 0.3 μm), the spacing between the two waveguides of the dual waveguide structure 2211 can be set to 1.2 μm, and the width of the two waveguides of the dual waveguide structure 2211 can be set to 0.16 μm.

[0050] In the embodiment of the present invention, by setting the second end of the first waveguide 221 as the dual waveguide structure 2211, the optical signal can be coupled and output from the two waveguides of the dual waveguide structure 2211 to the first end c1 of the optical polarization modulation unit 23. Compared with setting the second end of the first waveguide 221 as a single waveguide structure, it is helpful to excite a larger mode field at the second end of the first waveguide 221 and the mode field can be stably bound, so that the mode field can better match the mode field size of the first end c1 of the optical polarization modulation unit 23. Therefore, the mode field matching loss between the second end of the first waveguide 221 and the first end c1 of the optical polarization modulation unit 23 can be reduced, and the optical signal transmission efficiency can be improved.

[0051] Furthermore, by appropriately setting the distance between the two waveguides of the dual waveguide structure 2211 and the width of the two waveguides, the mode field matching degree can be maximized, thereby maximizing the light transmission efficiency.

[0052] It should be pointed out that regarding the waveguide structure setting of the second end of the first waveguide 221, the more waveguides there are, the better it is not the case. The main reason is that the more waveguide roots there are at the second end of the first waveguide 221, the more the mode field excited by its waveguide end face will mismatch with the mode field of the first end c1 of the optical polarization modulation unit 23.

[0053] Further, the total waveguide length of the first waveguide 221 is a first preset multiple of the width of the region where the first waveguide 221 is located; wherein the width direction of the region where the first waveguide 221 is located is consistent with the extension direction of the first end of the first waveguide 221 .

[0054] In a specific implementation, the width of the region where the first waveguide 221 is located may be less than or equal to the width of the first chip where the first waveguide 221 is located (eg Figure 2 h) shown in .

[0055] It should be noted that the ratio between the total length of the first waveguide 221 and the width of the region where the first waveguide 221 is located (i.e., the first preset multiple) should not be too large, otherwise it may lead to an increase in mode transmission loss; the first preset multiple should not be too small, otherwise it may not achieve the desired filtering effect. In practical applications, the optical detector 212 usually only needs to receive fundamental mode optical signals, so it is necessary to filter out the high-order modes in the optical signal returned from the optical polarization modulation unit 23.

[0056] In the embodiment of the present invention, on the basis of using the first waveguide 221 to realize the aforementioned mode field conversion function, by setting the first waveguide 221 to have a sufficient length value (that is, setting its length value to be several times the width of the area where it is located), the first waveguide 221 can also have a high-order mode suppression / filtering function for the return optical signal, so that the optical detector 212 can receive a more accurate and reliable fundamental mode optical signal, thereby improving the measurement accuracy of the fiber optic gyroscope.

[0057] Furthermore, the shape of the middle area of ​​the first waveguide 221 except the first end and the second end may be selected from but not limited to: a circular spiral shape and a square spiral shape.

[0058] In the embodiment of the present invention, the shape of the first waveguide 221 can be appropriately set under the premise of considering the process complexity, so that the first waveguide 221 occupies a smaller chip area to achieve the total length required for high-order mode filtering, thereby reducing the device size as much as possible.

[0059] Furthermore, the optical polarization modulation unit 23 may be formed in a second chip, the second chip comprising a lithium niobate layer and a second waveguide 231 formed in the lithium niobate layer; a first end of the second waveguide 231 is coupled to a second end of the first waveguide 221 .

[0060] The first end of the second waveguide 231 is located at the first end c1 of the optical polarization modulation unit 23 , and the second end of the second waveguide 231 is located at the second end c2 of the optical polarization modulation unit 23 .

[0061] In a specific implementation, the second waveguide 231 may be formed on the lithium niobate layer by an etching process or a proton diffusion process. In one specific implementation, the second chip may only include the lithium niobate layer. In another specific implementation, the second chip may include a substrate (e.g., a silicon substrate), and the lithium niobate layer is formed on the substrate.

[0062] Furthermore, the shape of the second waveguide 231 can be set to be Y-shaped; the optical signal output from the second end of the first waveguide 221 is divided into two-path optical signal outputs via the Y-shaped second waveguide 231 .

[0063] Furthermore, the second end of the first waveguide 221 is staggeredly coupled with the first end of the second waveguide 231 .

[0064] The direction of the misalignment is perpendicular to the extension direction of the first end of the second waveguide 231 and parallel to the surface of the substrate (or lithium niobate layer) of the second chip.

[0065] In a specific implementation, the misalignment between the second end of the first waveguide 221 and the first end of the second waveguide 231 in a direction perpendicular to the first end of the second waveguide 231 can be set within the interval [0.5 μm, 0.7 μm]. Further, in the case where the second end of the first waveguide 221 has the dual waveguide structure 2211, the first end of the second waveguide 231 can be set between the two waveguides of the dual waveguide structure 2211 (such as Figure 2 shown).

[0066] In the embodiment of the present invention, by setting the second end of the first waveguide 221 and the first end of the second waveguide 231 to be staggered coupled in the extension direction perpendicular to the first end of the second waveguide 231, it helps to further improve the matching degree of the mode field of the second end of the first waveguide 221 and the mode field of the first end of the second waveguide 231.

[0067] In a specific implementation, the optical integrated unit 21 can be formed on a silicon photonic chip, on which the optical coupling unit 211 and the light detector 212 are formed; the optical coupling unit 211 includes a first optical coupler 2111, an optical beam splitter 2113 and a second optical coupler 2112; the first end (located at a1) of the first optical coupler 2111 is coupled to the light source; the first end d1 of the optical beam splitter 2113 is coupled to the second end a1' of the first optical coupler 2111; the first end a2' of the second optical coupler 2112 is coupled to the second end d2 of the optical beam splitter 2113, and the second end (located at a2) of the second optical coupler 2112 is coupled to the first end (located at b1) of the first waveguide 221; the light detector 212 is coupled to the third end d3 of the optical beam splitter 2113.

[0068] Furthermore, a chip-to-chip coupling method may be used to couple the first end (located at b1) of the first waveguide 221 with the chip to which the optical coupling unit 211 belongs; and / or a chip-to-chip coupling method may be used to couple the second end (located at b2) of the first waveguide 221 with the first end of the second waveguide 231.

[0069] In an embodiment of the present invention, the waveguides at the output and / or input ends of each unit are coupled by adopting an inter-chip coupling method. Compared with the existing fiber optic gyroscope that couples each unit by using an optical fiber fusion splicing method, the inter-chip coupling method can avoid the splicing loss problem caused by optical fiber fusion splicing on the one hand, and further improve the optical signal transmission efficiency; on the other hand, compared with the optical fiber fusion splicing method, the inter-chip coupling method is not prone to breakage, the device structure is more stable, and it is easier to package subsequently.

[0070] Furthermore, one or more of the following conditions are satisfied: the waveguide width of the first end (located at b1) of the first waveguide 221 is in the interval [0.27 μm, 0.30 μm]; the waveguide width of the second end (located at b2) of the second optical coupler 2112 is in the interval [0.12 μm, 0.14 μm].

[0071] As a non-limiting embodiment, the waveguide width of the first end of the first waveguide 221 may be set to 0.28 μm, and the waveguide width of the second end of the second optical coupler 2112 may be set to 0.13 μm.

[0072] In the embodiment of the present invention, the mode field loss between the second end of the second optical coupler 2112 and the first end of the first waveguide 221, and the mode field loss between the second end of the first waveguide 221 and the first end of the second waveguide 231 are not only affected by the device material properties (for example, the light refractive index), but also by factors such as the waveguide width of the coupling end. Based on this, by appropriately setting the waveguide width of the first end of the first waveguide 221, the waveguide width of the second end of the second optical coupler 2112, and the waveguide width of the second end of the first waveguide 221, the mode field loss between the units can be reduced to the greatest extent.

[0073] It should be pointed out that, after research and simulation verification, by setting the waveguide width of the second end of the second optical coupler 2112 to be approximately 0.13 μm and the waveguide width of the first end of the first waveguide 221 to be approximately 0.28 μm, the inter-chip mode field overlap mismatch between the second end of the second optical coupler 2112 and the first end of the first waveguide 221 can be set to 0.09 dB, and the Fresnel reflection loss can be set to 0.000048 dB, that is, the total end face coupling loss between the two chips is less than 0.1 dB.

[0074] Furthermore, after research and simulation verification, by setting the spacing between the two waveguides of the dual waveguide structure 2211 at the second end of the first waveguide 221 to be approximately 1.2 μm and the width to be approximately 0.16 μm, the inter-chip mode field overlap mismatch between the second end of the first waveguide 221 and the first end of the second waveguide 231 can be set to 0.21 dB, and the Fresnel reflection loss can be set to 0.17 dB, that is, the total end face coupling loss between the two chips is less than 0.4 dB.

[0075] The embodiment of the present invention further provides a fiber optic gyroscope, comprising Figure 2 The optical component shown may also include a polarization-maintaining fiber ring (not shown in the figure); the polarization-maintaining fiber ring is coupled to the second end c2 of the optical polarization modulation unit 23, and the optical signal output by the optical polarization modulation unit 23 is returned to the optical polarization modulation unit 23 after the Sagnac effect occurs in the polarization-maintaining fiber ring.

[0076] For more details about the polarization-maintaining fiber ring, please refer to Figure 1 The related contents of the fiber optic gyroscope in the prior art are not described here. It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article indicates that the associated objects before and after are in an "or" relationship.

[0077] The "plurality" appearing in the embodiments of the present application refers to two or more.

[0078] The first, second, etc. descriptions appearing in the embodiments of the present application are only used for illustration and distinction of the description objects. There is no order, nor do they indicate any special limitation on the number of devices in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0079] It should be pointed out that the serial numbers of the steps in this embodiment do not limit the execution order of the steps.

[0080] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An optical component for a fiber optic gyroscope, characterized in that: include: Optical integration unit, mode field conversion unit and optical polarization modulation unit; The optical integrated unit comprises: an optical coupling unit and a light detector; The first end of the optical coupling unit is coupled to the light source, the second end of the optical coupling unit is coupled to the first end of the mode field conversion unit, the third end of the optical coupling unit is coupled to the photodetector, and the second end of the mode field conversion unit is coupled to the first end of the optical polarization modulation unit; The mode field conversion unit is used to perform mode field conversion on the optical signal output from the second end of the optical coupling unit and then input it into the optical polarization modulation unit, and to perform mode field conversion on the optical signal output from the first end of the optical polarization modulation unit and then couple it into the optical detector via the optical coupling unit.

2. The optical component according to claim 1, wherein: The mode field conversion unit is formed on a first chip, the first chip includes a silicon nitride layer, and a first waveguide formed on the silicon nitride layer; The first end of the first waveguide is coupled to the second end of the optical coupling unit, and the second end of the first waveguide is coupled to the first end of the optical polarization modulation unit.

3. The optical component according to claim 2, characterized in that The second end of the first waveguide has a double waveguide structure.

4. The optical component according to claim 3, satisfying one or more of the following: The distance between the two waveguides of the dual waveguide structure is in the interval [1.1 μm, 1.3 μm]; The widths of the two waveguides of the dual waveguide structure are both in the interval [0.15 μm, 0.18 μm]; The heights of the two waveguides of the dual waveguide structure are both within the range of [0.25 μm, 0.35 μm].

5. The optical component according to claim 2, wherein: The total waveguide length of the first waveguide is a first preset multiple of the width of the region where the first waveguide is located; The width direction of the region where the first waveguide is located is consistent with the extension direction of the first end of the first waveguide.

6. The optical component according to claim 5, characterized in that The shape of the middle area of ​​the first waveguide except the first end and the second end is selected from: a circular spiral shape and a square spiral shape.

7. The optical component according to claim 2 or 3, characterized in that: The optical polarization modulation unit is formed on a second chip, and the second chip includes a lithium niobate layer and a second waveguide formed on the lithium niobate layer; The first end of the second waveguide is coupled to the second end of the first waveguide.

8. The optical component according to claim 7, wherein: The shape of the second waveguide is Y-shaped; the optical signal output from the second end of the first waveguide is divided into two-path optical signal outputs via the Y-shaped second waveguide.

9. The optical component according to claim 7, wherein: The second end of the first waveguide is staggered coupled to the first end of the second waveguide.

10. The optical component according to claim 9, characterized in that The misalignment between the second end of the first waveguide and the first end of the second waveguide in a direction perpendicular to the first end of the second waveguide is in the interval [0.5 μm, 0.7 μm].

11. The optical component according to claim 7, wherein: Adopting an inter-chip coupling method to couple the first end of the first waveguide with the chip to which the optical coupling unit belongs; and / or, The second end of the first waveguide is coupled to the first end of the second waveguide by using an inter-chip coupling method.

12. The optical component according to claim 2, wherein: The optical integration unit is formed on a silicon photonic chip, and the optical coupling unit and the light detector are formed on the silicon photonic chip; The optical coupling unit includes a first optical coupler, an optical beam splitter and a second optical coupler; The first end of the first optical coupler is coupled to the light source; The first end of the optical beam splitter is coupled to the second end of the first optical coupler; The first end of the second optical coupler is coupled to the second end of the optical beam splitter, and the second end of the second optical coupler is coupled to the first end of the first waveguide; The optical detector is coupled to the third end of the optical beam splitter.

13. The optical component according to claim 12, wherein: Meet one or more of the following: The waveguide width of the first end of the first waveguide is in the interval [0.27 μm, 0.30 μm]; The waveguide width of the second end of the second optical coupler is in the interval [0.12 μm, 0.14 μm].

14. A fiber optic gyroscope, characterized in that: comprising the optical assembly and polarization-maintaining optical fiber ring according to any one of claims 1 to 13; The polarization-maintaining fiber ring is coupled to the second end of the optical polarization modulation unit, and the optical signal output by the optical polarization modulation unit is returned to the optical polarization modulation unit after the Sagnac effect occurs in the polarization-maintaining fiber ring.

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